Synthetic lubricant and method of making same



Patented'18; loss Edgar GBritton. llidhnd, lllehs assignorto TheDowChemicalompany,Midland,lllch-, acorporationoflllchim No Drawing. Application August 1, 1934.

Serial 4 Claim!- (01. 87 -9) The present invention relates to a method for the thermal decomposition of diphenyloxide (CGHLOCQHQ whereby an oleaginous Product is formed which marked stability at elevated temperatures coupled with excellent lubricating properties. I

I have found that when dipherlyloxide is heated at atmospheric or higher pressure to a tem- 0 perature between about 100 and 800 6., and

maintained at such temperature for a sufficient length of time, depending upon the temperature employed, it undergoes a partial'conversion to form a complex mixture of compounds having a higher boiling point and a higher molecular weight than the starting material. Certain of such compoimds are similar in appearance to oils derived from a petroleum base, but differentiating therefrom in various important respects, such as specific gravity, ability to withstand high temperatures without decomposing, chemical behavior, etc.

The rate of conversion of diphenyloxide to the higher boiling oleaginous products is dependent upon the temperature at which it is treated. For

ture from 400 to 450 C. the conversion to the higher boiling oil was only about 2 per cent. At higher temperatures, however, the ratio was initially increased to as much as 15 per cent conversion in 3 minutes at 650 to 700"C4, but the accumulation of conversion product in the mixture appears to limit further change upon continued heating after about 15 per cent of product has been formed.

If the unaltered material remaining is distilled 0E, however, and then subjected to the same thermal treatment, a further conversion may be effected and the process repeated until 40 the larger part of the original material has been transformed to the desired high boiling oil.

The new products or oils are separated by distillation from the mixture resulting from the aforesaid thermal treatment of diphenyloxide.

The lower boiling compounds and unreacted material are first distilled oil, and then the higherboiling fractions constituting my new oils are distilled over, preferably under reduced pressure, the boiling point range thereof being about 200 to 350 C. at 5 .to 10 millimeters absolute pressure.

The physical propertiesof my new oils or of fractions obtained therefrom are approximately as follows:-

. 8o Dielectric strength. 25x10= volts per 0.1 in. gap.

example, when heated for '1 days at a tempera- The color is reddish yellow by transmitted light, changing to dark green by reflected light, the oils exhibiting a fluorescence similar to that of paramn base oils.

The identity and chemical constitution of the 5 compounds comprising my new oils have not been determined. The oils are dissolved on warming with fuming sulphuric acid and are likewise readily soluble in dimethyl sulphate, thus responding to tests'lndicating them to be com- 10 posed substantially of aromatic hydrocarbons or oxygenated derivatives thereof. The last named feature particularly distinguishes the oils of the present invention from the oils derived from a petroleum base or produced by synthetic methods 15 from coal or natural bituminous substances. The average molecular weight of the constituents of the oils is in the vicinity of 300 according to the usual methods of determination, although apparently the range of molecular weights of the various components extends from about 250 to 350 or hi her.

A representative ultimate analysis of a sample of the oils is as followsz-carbon, 87.12 per cent; hydrogen, 5.49 per cent; oxygen (by dim), 7.34 25 per cent; ash, 0.05 per cent. Naturally there will be more or less variation in the analysis of diiferentsamples, and the above figures are not to be construed as l miting the invention.

, A striking property of my new oils is their exceptional stability when exposed to elevated temperatures. For instance, they may be heated repeatedly and for long periods to temperatures as high as 400 C. without material deterioration or modification of their properties. In one test .a sample maintained; continuously for one week at a temperature of 400 0. showed no carbonization and suilered no loss in body or viscosity. As contrasted thereto samples of good commercialgrades of heavy" motor'oil subjected to the same treatment were extensively carbonized and broken down to a consistency much like water so that their lubricating value was completely destroyed.

This ability to withstand prolonged exposure to a high degree of heat demonstrates the superiority of the oils for a variety of purposes, such as for the lubrication of. Diesel engines, steam-engines and all forms of mechanical apparatus operated at bearing temperatures as high as about 50 400' C. The oils are likewise well. adapted for 7 use as a heat transfer medium.

eir high dielectric strength, in addition, ,1! them particularly for use as transformer/oils, and for similar applications. Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the method herein disclosed, provided the step or stepss'tatedby anyofthefollowlngclaimsortheoo equivalent of such stated step or steps be em-- ployed. r

I therefore p'articularly point out and distinctly claim as my invention:-

1. The method of making oleaginous products which comprises heating diphenyloxide at a temperature between 400C, and the decomposition point thereof and. separating from the reaction product the fraction distilling between approximately 200 and 350 C. at an absolute pressure of 5 to 10 millimeters.

2. The method of making oleaginous products which comprises heating diphenyloxide at a temperature between about 650 and 750 C. under pressure due to the vapor pressure of the reaction mixture at the temperature employed and separating from the reaction-product the fraction distilling between approximately 200 and 350 C. at an absolute pressure of 5 to 10 millimeters.

3. An oil comprising the product of the thermal treatment of diphenyloxide or mixtures of the same with aromatic hydrocarbons and exygenated derivatives thereof at a temperature between 400 C. and the decomposition point of such compounds, said product having a specific gravity between 1.12 and 1.21 at C. and a viscosity between 40 and sec. Saybolt at 210 F.,

V and being completely soluble on warming with fuming sulphuric acid.

4. The method of making oleaginous products which comprises heating diphenyl oxide to a temperature between about 400 C. and below the temperature at which decomposition of the di phenyl oxide occurs while maintained under superatmospheric pressure, and separating from the reaction product the fraction distilling between 200 and 350 C. at an absolute pressure of 5 to 10 millimeters.

EDGAR C. BRI'I'ION 

